✅19 - Populations In Ecosystems Flashcards
What is ecology?
The study of inter-relationships between organisms
What are the two main processes to consider within an ecosystem?
- the flow of energy through the system
- the cycling of elements within the system
What is a population?
A group of individuals of one species that occupy the same habitat at the same time and are able to interbreed
What is a carrying capacity?
The size of population of a species which an ecosystem can support
What can causes population sizes to vary?
The effect of abiotic factors
Interacts between organisms, eg intraspecific and interspecific competition
What is a community?
All the populations of different species living and interacting in a particular place at the same time
What is a habitat?
The place where an organism normally lives and is characterised by physical conditions and the other types of organisms present
What are microhabitats?
Smaller units with their own microclimates within a habitat
What is an ecological niche?
It describes how an organism fits into its environment and refers to where an organism lives and what it does there
What does a niche include?
All the biotic and abiotic conditions to which an organism is adapted in order to survive, reproduce and maintain a viable population
What is the competitive exclusion principle?
No two species occupy exactly the same niche
What is population size?
The number of individuals in a population
What are abiotic factors which influence the size of a population?
Temperature
Light
pH
Water/humidity
How does temperature affect the size of a population?
Each species has an optimum temperature, and the further from the optimum, the fewer individuals survive. Enzymes work more slowly so metabolic rate is reduced and they may denature
How does light affect the size of a population?
As the ultimate source of energy for most ecosystems, light is a basic need. The rate of photosynthesis crashes as light intensity increases. This increases growth and carrying capacity for animals that feed on the plants
How does pH affect size of population?
It affects the action of enzymes, as each enzyme has an optimum pH at which it operates most efficiently. A population of organisms is larger where the appropriate pH exists
How do water and humidity affect population size?
Where water is scarce, populations are small and consist only of well adapted species. Humidity affects transpiration rate in plants and water loss from the bodies of animals
What is immigration?
Where individuals join a population from outside
What is emigration?
Where individuals leave a population
Population growth =
(Births + immigration) - (deaths + emigration)